Biomechanical comparison of extended trochanteric osteotomy and slot osteotomy for femoral component revision in total hip arthroplasty

Background. Depending upon the clinical presentation and need for exposure in revision hip arthroplasty, an extended trochanteric osteotomy or slot osteotomy could be used for removal of an inaccessible distal cement mantle, infected material, or distal fragment of a broken stem. This study is a biomechanical comparison of these two osteotomy techniques. Methods. A press-fit femoral component with a 20-cm straight stem was implanted in each of ten synthetic femurs. The stiffness of these components implanted in the femurs was measured for a compressive load condition simulating the stance phase of level walking. Half of the femurs then received an extended trochanteric osteotomy, and the other half a slot osteotomy. Stiffness testing was repeated both after the osteotomized bone was removed, and after it was fixed back in place by cerclage wiring. Findings. The stiffness of the femoral component/synthetic femur constructs in the slot osteotomy group was significantly greater than in the extended trochanteric osteotomy group. Interpretation. This study demonstrated that in the laboratory setting, the slot osteotomy was significantly stiffer than the more traditional extended trochanteric osteotomy. However, the clinical implications of this increased stiffness are unknown. The ultimate choice of the type of osteotomy depends upon the exposure requirements for a given clinical situation.